Biotransformation of glycyrrhizin by human intestinal bacteria and its relation to biological activities

The relationship between the metabolites of glycyrrhizin (18 beta-glycyrrhetinic acid-3-O-beta-D-glucuronopyranosyl-(1-->2)-beta-D-glucuronide, GL) and their biological activities was investigated. By human intestinal microflora, GL was metabolized to 18 beta-glycyrrhetinic acid (GA) as a main product and to 18P-glycyrrhetinic acid-3-O-beta-D-glufuronide (GAMG) as a miner product. The former reaction was catalyzed by Eubacterium L-8 and the latter was by Streptococcus LJ-22. Among GL and its metabolites, GA and GAMG had more patent in vitro anti-platelet aggregation activity than Gt. GA also showed the most patent cytotoxicity against tumor cell lines and the potent inhibitory activity on rotavirus infection as well as growth of Helicobacter pylori. GAMG, the minor metabolite of GL, was the sweetest.